title: Combined semirigid and flexible ureterorenoscopy via a large ureteral access sheath for kidney stones >2 cm: a bicentric prospective assessment.
abstract: OBJECTIVE
  The international guidelines on urolithiasis state that the percutaneous approach is superior for kidney stones ≥20 mm. Nevertheless, several groups have reported high stone-free rates (SFRs) with low morbidity for ureteroscopic treatment of calculi >15 mm. We hereby describe a new technique including the combined use of semirigid and flexible ureteroscopy via a large ureteral access sheath (UAS).
  
  
  METHODS
  The proposed technique includes (a) preoperative ureteral stenting, (b) use of a large lumen UAS (14/16F, 35 cm), (c) use of a semirigid ureteroscope, (d) holmium laser lithotripsy, (e) passive and (f) active fragment extraction, and finally, the removal of caliceal stones (g) using a flexible scope. We conducted a prospective outcome analysis for 38 patients treated at two tertiary university centers.
  
  
  RESULTS
  Perioperative data were as follows: median cumulative stone size 24.5 mm (20-60), median operating time 95 min (50-205), post-operative ureteral stenting (2-35 days) in 33 patients (86.8 %), Clavien complications 2 and 3 in 7.9 %, primary SFR 63.2 %, and overall computed tomography (CT) controlled SFR after 3 months 81.8 % (including staged procedures). No late complications were observed.
  
  
  CONCLUSIONS
  The combined use of semirigid ureteroscopy and an UAS further develops the endoscopic treatment of kidney stones. This is the first series of this kind that confirms high SFRs by CT. The approach has significant advantages: Superior irrigation and outflow enhance both vision and stone clearance, and multiple ureteral passages without putting the ureter at injury risk. These encouraging results make this modality an appealing alternative to percutaneous nephrolithotomy.
authors.affiliation: Department of Urology, University Medical Centre, Hugstetterstr. 55, 79106, Freiburg, Germany, arkadiusz.miernik@uniklinik-freiburg.de.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Miernik
authors.forename: Martin
authors.initials: M
authors.lastname: Schoenthaler
authors.forename: Konrad
authors.initials: K
authors.lastname: Wilhelm
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wetterauer
authors.forename: Marcin
authors.initials: M
authors.lastname: Zyczkowski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Paradysz
authors.forename: Piotr
authors.initials: P
authors.lastname: Bryniarski
mesh_terms: D000328:Adult; D000368:Aged; D004867:Equipment Design; D005260:Female; D005471:Fluoroscopy; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D007669:Kidney Calculi / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D020709:Ureteroscopes; D018666:Ureteroscopy / Q000379:methods*; D055815:Young Adult